Stiffening panels for flexible walled containers



Dec. 10, 1957 J. D. THOMPSON 2,315,898

STIFF'ENING PANELS FOR FLEXIBLE WALLED CONTAINERS Filed .331} 12, 1952 3 Sheets-Sheet l Fl W uvwszv TOR. J)! Y 0. 77101141 50 ATroRA/E VS Dec. 10, 1957 .1. D. THOMPSON STIFFENING PANELS FOR FLEXIBLE WALLED CONTAINERS Filed Jan. 12, 1952 3 Sheets-Sheet 2 INVENTOR. J14 Y D. THOMPJON Fla. /3

Arron/vex;

Dec. 10, 1957 J. D. THOMPSON 2,315,398

STIFFENING PANELS FOR FLEXIBLE WAL L-ED CONTAINERS Filed Jan. 12, 1952 3 Sheets-Sheet 3 INVEN TOR. J r 0. 7;IOMPJOIY mwwwwm United States Patent STIFFENING PANELS FOR FLEXIBLE WALLED CONTAINERS Jay D. Thompson, Minneapolis, Minn., assignor to Bemis Bro. Bag Company, Minneapolis, Minn., a corporation of Missouri Application January 12, 1952, Serial No. 266,122

14 Claims. (Cl. 229-55) This invention relates to improvements in the construction of containers made of paper, light cardboard, cloth and other flexible materials that are used for the packaging and display of bulk material, such as flour, cereal, sugar, soap powders and the like commodities.

Such containers usually have indicia, such as trademarks, type and amount of merchandise, the commodity manufacturer's name, etc., printed on the sheet from which the package is formed with the object in view of displaying' the indicia on a fiat or nearly flat face of the container when it is filled and placed on a display shelf. The containers are usually made so they can be folded fiat, for example a fiat-fold or intucked" (or infold) bag, so as to conserve shipping space of the unfilled containers. The containers are opened by the commodity manufacturer at his establishment and filled with the commodity and are then closed and sealed. The containers, when thus filled, form their own display when ultimately placed upon the merchants shelf, and the flexible walled bag (container) design is usually such that it is at least supposed to produce a filled container of rectangular parallelepipedon configuration having two major (front and back) rectangular faces and smooth or nearly smooth rectangular bottoms and side panels of lesser area than the front and back faces. It is also desired to have neat folds at all edges and corners.

In practice, however, these objects of prior art flexible walled containers are only indifferently achieved due to the rounding effect caused by the pressure of the packaged bulk solid material. Thus, flour, sugar, coffee and most bulk materials have a low angle of repose and fiow," thus exerting a pressure in the container somewhat analogous to gas pressure. This pressure" of the commodity tends to change the shape of the container from a neat rectangular parallelepipedon to a rounded shape more nearly approaching a sphere. As a result, flexible walled containers (bags and the like) have always been subject to the infirmity that the front, back, side and end panels tend to bulge and the edges and corners become rounded rather than neat and sharp. The greater the difference between the area (practically the side-to-side width) of the front-back as compared with the area (practically, the front-to-back dimension) of the sides and ends in the theoretical bag shape, the more pronouncedwill be the bulging and rounding effects due to the aforesaid pressure when the bag is filled. Statedanother way, a very fiat theoretical bag shape will exhibit a greater tendency of the fiat front and back faces to bulge and the edges and corners to round than one in which the front and back panels more nearly approach the area of the sides and ends.

Accordingly, in the design of flexible walled containers and flat foldable containers, there have been practical limits beyond which the bag designer could not usually go and as a result the front and back panels of usual flexible walled bag designs have not usually had a sideto-side width which muchexceeded 1% to 2 times the front to back dimension of the-side and end panels and 2,815,898 Patented Dec. 10, 1957 even then the aforesaid bulging and rounding has had to be tolerated as a problem heretofore incapable of economical solution.

From the merchandising standpoint in competitive markets it is desirable to have as much space as possible on the front and back of the bag so as to allow prominent display of trade-marks, etc., but provision of such space has been rendered impossible in packaged goods except by the use of rigid boxes made of strong paperboard having inherent stiffnesses sufiicient to withstand the aforesaid distorting pressure of the commodity within the package. However, use of such rigid packages is limited, since when empty they cannot be shipped economically after being set up because of the large space they occupy and hence are usually fabricated by large and expensive machinery at the place where they are to be filled with the commodity. In addition, the cost of rigid cardboard generally exceeds the cost of paper.

It is an object of the present invention to provide an improved flexible wall container, which is economical to make and ship, capable of being folded flat when empty, is constructed so as to resist bulging and rounding and more nearly resembles a box in appearance when it is filled and closed.

It is a further object of the invention to provide an improved flexible walled container capable of being folded flat for storage and yet capable of being set up into a relatively flat rectangular package presenting flat front and rear panels with neat edges and corners.

It is a further object of the invention to provide an improved bag structure having reinforcement capable of maintaining selected panels of the filled bag in fiat neat condition.

It is a further object of the invention to provide an improved bag structure capable of being set up and filled to provide a package of substantially rectangular parallelepipedon configuration wherein the front and back faces are relatively much greater in width as compared to the sides, than has heretofore been possible in such bag structures.

It is a further object of the invention to provide a flexible walled bag structure wherein reinforcements are provided throughout substantially the entire extent of selected faces of the bag when filled.

It is another object of the invention to provide flexible wall bags having stiffening panels designed to hold the bag in a predetermined form or shape when it is filled and closed without, however, causing rupture of the flexible bag wall material along the edge of the stiffening panel.

it is a further object of this invention to provide an improved flexible walled container having a stiff reinforcement panel, wherein the edge portions of the panel are weakened so as to allow the edge to bend slightly in a transverse direction in conformance with the bending of the flexible wall of said container when the bag is filled and with the flexible material of the container wall form a neat short radius bend thereby enabling gradual transfer of stresses from the stiff reinforcement panel to the wall member.

.It is still another object of this invention to provide improved 'flcxible bag construction having a stiff reinforcement panel with edges progressively outwardly weakened so as to allow the weakened edge to deflect and thereby progressively transfer stresses between the panel and bag wall.

Other and further objects of the invention are those inherent in the apparatus herein illustrated, described and claimed.

The invention is illustrated with reference to the drawings in which corresponding numerals refer to the same parts.

Figure l is a front elevational view, partially broken away, showing stiff reinforcement panels with weakened edges on the inside of a flexible container;

Figure 2 is a horizontal sectional view taken along the line and in the direction of arrows 2-2 of Figure 1;

Figure 3 is a fragmentary vertical sectional view taken along the line and in the direction of arrows 33 of Figure 2;

Figure 4 is a perspective view partially broken away showing a container with stiff reinforcement panels according to the present invention;

Figure 5 is a horizontal sectional view showing a filled flexible walled container of the present invention;

Figure 6 is a side elevational view partially broken away showing a filled flexible walled container of the present invention;

Figures 7, 8 and 9 are a series of related views in which Figure 7 is an enlarged fragmentary elevational view taken from the inside of a container constructed in accordance with the present invention, showing one method of progressively weakening the edge of a stilfening panel; Figure 8 is a vertical sectional view taken along the line and in the direction of arrows 8-8 of Figure 7, showing the bag wall and panel when flat; and Figure 9 is a vertical sectional view corresponding to Figure 8, but illustrating the action of the weakened edges of the reinforcing panel when the flexible wall of the container is bent therearound at ninety degrees as when the bag is filled and closed.

Figures 10, 11 and 12 are another series of related views in which Figure 10 is an enlarged fragmentary elevational view taken from the inside of the container showing another form of panel having a differently weakened edge; Figure 11 is a vertical sectional view taken along the line and in the direction of arrows 1111 of Figure 10, showing the bag wall and panel when flat; and Figure 12 is a vertical sectional view corresponding to Figure 11, but illustrating the action of the weakened edges of the reinforcing panel when the flexible wall of the container is bent therearound at ninety degrees, as when the bag is filled and closed.

Figures 13, 14 and are another series of related views in which Figure 13 is an enlarged fragmentary elevational view taken from the inside of the container showing still another modified form of panel; Figure 14 is a vertical sectional view taken along the line and in the direction of arrows 14-14 of Figure 13, showing the bag wall and panel when flat; and Figure 15 is a vertical sectional view corresponding to Figure 14, but illustrating the action of the weakened edges of the panel when the container is filled and the flexible container wall is folded therearound;

Figure 16 is a perspective view, partially broken away, of another typical form of flexible walled showing, in this instance, a modified form of stiffening panel, the panel being of such extent as to cover the two principal faces of the bag and also the bottom;

Figure 17 is a side elevational view partially broken away, of a filled and closed container unit corresponding to that shown in Figure 16, illustrating the action of the reinforcing panel and particularly the action of weakened edges of the panel when the container wall is bent therearound;

Figures 18 and 19 are perspective views, each partially broken away, of still other flexible walled containers embodying the present invention.

In accordance with the present invention the stiffen ing insert panels may be used on the inside of any face of the bag which it is desired to reinforce and stabilize against bulging and which is not outwardly folded when the bag is flat. Several illustrations of reinforcement of different faces of the container are herein contained and exemplify the invention. Thus, in Figures 16, only the principal (largest) faces of the bag are stiffened, namely the large-area front and back panels 11 and 12. This is frequently sufficient for practical packaging. More reinforcement may, however, be provided as in Figures 16 and 17, where the front, bottom and back are reinforced as an articulated unit, the bottom area infolding along its transverse centerline as in Figure 3 in conformance with the bag fold, when the bag is folded flat. In Figure 18 the reinforcement covers the front and back panels (or faces, however designated) and extends in each instance around the side bends and partially over the adjacent sides of the bag. The flexible bag itself in Figure 18 can be either the infold or outfold type, preferably the latter, because with the reinforcement panel the completed bag stacks better when folded. In Figure 19 there is shown another system of reinforcement covering the front, back, most of the sides of the bag, the reinforcement folding in at the vertical centerline of the sides in conformance with the bag wall infold.

Throughout the present invention the wall area reinforcement members have the common characteristic of having all or some of their marginal edges weakened so as to permit such marginal edges to bend slightly and thereby form neat short radius edges and assist in transferring stresses between the flexible bag material and the reinforcing panel where the panels terminate. Without such flexible margins (and consequent controlled bending and gradual load transfer) the flexible bag material, per se, is prone to rupture, or stated another way, a greater strength than average flexible sheet material may be required.

Referring to the drawings, particularly Figures 1-6, and 7-9 there is illustrated a typical form of flexible walled container made in accordance with the present invention. In these figures there is illustrated what is known as a flat fold bag, Figures 1-3 showing the folded or nearly folded position. According to this bag construction, the outer flexible material of which the bag is made, can be paper, cloth, plastics or the like, and composed of one or several plies, has a front panel or front" 11 extending across the dimension 11A, and a back panel or back 12 extending across the dimension 12A. The front begins at the bottom fold 13 and extends to the top of the bag 14, the normal line to which the bag is filled in service being at the line 1515 in Figure 1. The side panels or sides of the bag are composed of the parts 16A and 16B for the right-hand side, which form one relatively flat surface when the bag is opened. The left side of the bag is composed of the parts 17A and 17B which likewise form one flat surface when the bag is opened. The bottom of the bag is composed of the portion 18A and 188 which fold down from the infolded position of Figures 1-3 to a flat position, as shown in Figures 4 and 6, when the bag is filled.

According to this illustrative embodiment of the invention, stiff reinforcing panels of cardboard, paperboard, plastic or the like are provided, which are substantially coextensive with the width and height of the front and rear faces 11 and 12 of the bag. These stiff reinforcing panels are designated 20 for the rear panel and 21 for the front panel.

According to this invention the marginal edges of the stiff reinforcing panels 20-21 are weakened so that they will bend transversely with a lesser amount of force than is required to bend the reinforcing panel generally.

A wide variety of methods may be utilized for slightly weakening the marginal edge of the panel. Thus, one method is simply roughly to tear off the panel, after it has been scored just enough to guide the tear. Such tearing is not even and leaves a ragged edge (not straight) which therefore provides a random marginal area which is weakened, as compared with the remainder of the panel. Another method is to cut the panel, either completely or partially, through with a knife that is serrated or undulated along the cut. One such serrated" edge cut is illustrated in Figures l-6. The tips of the r serrations are the weakest portions and accordingly easily bend, the base of the serrations being stronger.

Several different ways of providing such serrations are shown in the sets of Figures 7-9; Figures 10-12 and Figures 13-15. Thus, in Figures 7-9 the edge of the reinforcing panel P is provided with sawtooth serrations 22-22 completely cut through. The tip portions 22A of these serrations are relatively much weaker than the base portions 22B and accordingly the tips bend transversely and, with the overlying flexible wall, form a neat short radius bend, thus distributing transfer of stresses between the panel P and the flexible bag wall F, as shown in Figure 9. The panel P is ordinarily adhesively attached to the bag wall F by dryable or heat setting cement and when in the flat folded condition the panel lies in contact with the bag wall F as illustrated. The adhesive is preferably not carried entirely to the edge of the serrations, thus being kept below the line 24 in Figure 8, with the result that the serrations proper will be free to creep" slightly in response to the change in form from Figure 8 to Figure 9. As a result when the bag is filled and a bend occurs, as at the margins of the reinforcing panels -21 of the bag shown in Figures 16, the flexible bag wall F (Figure 9) will impose a stress on the serrations 22 (or vice versa) and cause them to bend to a neat short radius from the position shown in Figure 8 to the position shown in Figure 9. The serrations bend according to a short radius R, as shown in Figure 9, and thus distribute the bend in the flexible bag wall over a neat but yet distributed area, as shown by the dimension D of Figure 9. The depth of the serrations controls to some extent the radius of the bend.

Other forms of weakening the edges of the reinforcing panels may be used. Thus, in Figures 10-12 the panel P is provided with a cut along a serrated line, but the cut does not extend entirely through the panel which is preferably of glazed material. After cutting the panel is then completely torn off. Thus, the panel P is cut along the line 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34. The cut is not entirely through the thickness T of the panel and then when the panel is torn it will tear away at the surfaces 36, 37, 38, 39 and 40. It will be noted that the portion of these surfaces which is nearest the lines 41-42 tends to be thinner than the portion nearer the points 25, 27, 29, 31 and 33 and accordingly there is, in effect, a chamfering action which facilitates the bending desired. At the same time the surface 43 of the reinforcing panel P is uninterrupted throughout the panel even out to the line 41-42, and accordingly serves to prevent concentrations of stress against the flexible bag wall F. The bend achieved when the flexible bag is set up and filled, is illustrated in Figure 12.

In Figures 13-15 another system of weakening the edge of the reinforcing panel P is illustrated. in this method the panel P has its marginal edge E thinned out along a slanting line 45, Figure 14, which can be done either by cutting, skiving or by grinding, using a coarse wheel. The panels are first cut sharply and then can be passed under a coarse grinding wheel, wire brush or the like, which serves to remove the material shown in the stipplcd area 46, Figure 14, thus leaving a chamfered marginal edge E on which the panel P, which is accordingly weaker and more likely to bend than is the panel proper. As a result when the bag is set up and filled and the flexible wall F is caused to bend at right angles, as shown in Figure 15, the panel P assumes a curve as shown in Figure 15, throughout the marginal area E, with the result that the stresses are transferred as be tween the panel and the flexible wall F, as shown by the dimension D, Figure 15.

Other methods of weakening the marginal edge of the reinforcing panel will suggest themselves. Thus, the serrations need not be sawtooth, but may be undulent.

.Likewise, a marginal area of the panel may be provided with a plurality of fine perforations located so as gradually to reduce the net amount of material available towardsthe edge of the panel. Many other systems of weakening are available but those illustrated are preferred because they may be obtained at least cost.

Referring to Figures l-6, the reinforcing panel, as previously stated is substantially coextensive with the theoretical front and back areas of the rectangular parallelepipedon bag and the marginal edges of the panel are sufflciently weakened so as to provide an area E, on both of the panels 20 and 21, which is weakened, as compared with the normal stiffness of the board from which the panels are made and readily capable of bending transversely. In the form of construction shown, the sawtooth edge euts are used and these may be either the form shown in Figures 7-9 or the form shown in Figures 10-42. The weakened margin E extends entirely around the panels. When the bag is opened and filled, the top portion 93 and 94 of the front and back panels, and the top portions 52 and 53 of the side panels 16 and 17 are folded down in the normal manner, thus forming a top closure as shown generally at 54 in Figure 6. The top closure and fold occurs so as to bring the front flexible wall 11 over the upper edge 21A of the front reinforcing panel 21 and the back panel 12 is folded so as to fold over the upper edge 20A of the rear reinforcing panel 20. In setting up the bag, the bottom 18, of course, folds downand the pressure of the material within likewise presses out against the panel, causing the bottom portion 18 of the flexible bag to be drawn tightly around the lower edge 21B of the front reinforcing panel 21 and the lower edge 20B of the rear reinforcing panel 20. Similarly, the sides 16 and 17 are drawn around the side edges 21C and 21D of the front reinforcing panel, and the side edges 20C and 20D of the rear reinforcing panel. The stresses in the flexible wall of the bag are thus concentrated around the margins of the reinforcing panels and in so doing they cause the weakened marginal edge E all around such panels to deflect slightly, as shown in Figures 5 and 6.

The net effect of using the reinforcing panels is to cause the filled bag to much more nearly resemble a rectangular parallelepipedon in shape. By way of comparison an unreinforced flexible bag filled with coffee, sugar, flour or the like will assume a shape similar to that shown by the dotted line in Figures 5 and 6. Thus, having the front bulging portion 50, the rear bulging portion 51 and corner radii of long radius such as at 56A, 50B, 51A and 518 in Figure 5 and at 50C and 56D, 51C and 51D in Figure 6. By including the reinforcing panels in the structure, the front and back panels are maintained substantially level and flat and the edges of the panels are nearly square corners. Furthermore, the total width of the front and rear panels may be a substantially greater multiple of the width of the side panels than has been possible in prior bags, thus making available for the first time flat, thin, flexible wall bags. Previously, the front and rear panels of the flexible walled bags could not greatly exceed the width of the side panels.

Referring to Figure 16 there is illustrated a form of reinforcement panel generally designated 55 which is shaped so as to have a front portion 56 which has a width and height substantially coextensive with the front panel of the bag when it is filled and closed, the normal filling line of the bag being substantially at the line 57-57. The reinforcing member 55 also has a portion 58 which extends across the bottom of the bag and a portion 59 which extends up the rear panel of the bag. All of the parts 56, 58 and 59 are from a single piece of relatively stiff cardboard, and the marginal edges of the entire piece are treated so as to be weakened. Thus, as illustrated, all of the marginal edges of the entire member SSare provided with serrations 60. This bag is of the flat fold type and the bottom 58 folds upward as shown in Figure 1. Consequently, the bottom reinforcing member has a bend at 61 and bends at the bottom corners 62 and 63. When this form of bag is filled, the bottom part 58 folds down to the form illustrated in Figure 16, and in so doing exerts a toggle action which forces the corners 62 and 63 firmly outwardly against the flexible outer bag wall, front and back walls 64 and 65. Then the bag is filled with the bulk solid material S to the level of the line 57 and the upper portions of the bag folded down and the closure made in the usual way as at 66. The bulk granular material tends to bulge out the front and the side panels of the bag, as well as the bottom and top. Since the bag is usually set on the shelf the bottom is held more or less fiat and this action is assisted by the bottom reinforcement panel 58. At the same time the front portion 56 of the reinforcing member and the back portion 59 of the reinforcing member serve to hold nearly flat the front and back panels 64 and 65 and the flexible material constituting the bag is drawn relatively tightly around the weakened vertical edges 67 and 68 of the front portion 56 of the reinforcing member and around the vertical edges 69 and 70 of the rear portion 59 of the reinforcing member. At the same time the top fold likewise is drawn relatively tight around the top edge 72 of the front portion 56 of the reinforcing member and the top edge 73 of the rear portion 59 of the reinforcing member. All of these edges have a marginal weakened portion and consequently they bend slightly as described previously with the form of reinforcing device shown in Figures 1-6. This is also illustrated by the bent over weakened edge 72 and the bent over weakened edge 73 as shown in Figure 17. Accordingly, the bag is held in a substantially rectangular parallelepipedon form and yet where the flexible bag wall material goes around the corner or edge it is held relatively smoothly around a neat radius and stress concentration sufficient to break the paper of the flexible bag wall or other flexible material is avoided.

Referring to Figure 18 another form of bag reinforcement is illustrated. In this instance the bag which is of flexible material is provided with a front reinforcing member generally designated 81 and a rear reinforcing member generally designated 96. These are of an area such that they extend completely across the Width W of the front and back of the bag and the reinforcing members are bent at the side edges 82 and 83 of the front panel of the bag and the side edges 84 and 85 of the rear panel of the bag and the reinforcing member extends a short distance onto the side panels 86 and 87 of the bag. The reinforcing members 81 and 96 are cut away at 88, 89, 90 and 91 to accommodate the upfolding of the bottom 92 when the bag is folded flat after manufacture and prior to filling. members 81 and 96 have their marginal edges weakened entirely around in this instance by utilizing serrated cuts along the edges. Of course, any other form of weakening method may be used, as previously described. As a result when the bag is filled to the level of line 95 and closed, it is maintained substantially in the form of a rectangular parallelepipedon, the edges 82 through 85 in this instance being maintained firmly by the underlying folded reinforcing member. Accordingly, the stresses are trans ferred around the bent reinforcing member and at the top and bottom edges of the reinforcing member where the bag wall flexible material is folded around, stress concentration is avoided by the weakened edges which are bent as previously described.

Referring to Figure l9 there is illustrated a further form of flexible walled container or bag having a reinforcing member provided with marginally weakened edges. In this form the bag generally designated 100 is of the infold type, both the bottom and the sides being infolded when the bag is flat prior to filling. Within the bag, and extending from the bottom to the filling line at 101101, there is provided a liner of relatively stiff cardboard which extends entirely around the front Wall, right side wall, rear wall and left side wall. This liner, which is thus an openended tube is provided at its upper edge with a In this form of construction reinforcing weakened margin as at 102-102 and the bottom marginal edge of the tube is likewise weakened as at 103 for the front panel and 104 for the back panel. It is noted that the sides of this reinforcing tube are upwardly out toward the median line 105 so as to accommodate the infolding of the bottom when the bag is flat. Accordingly, to accommodate this infolding of the bottom 106 the lower margins 107 and 108 of the side wall 109 of the reinforcing cardboard tube are cut away at an appropriate angle and these edges. if desired, may likewise have a marginal weakening, as by providing the serrations shown. The same is true for the edges 110 and 111.

The special advantage of this form of bag construction is that when the bag is filled the portions 109, 109A and 109B of the side wall 109, which are infolded about the line 105 when the bag is flat folded, and the portions 113A and 113B of the side wall 113, which are likewise infolded about the median line 105, serve to produce a toggling action which applies outward stretching force to the circumference of the bag and accordingly pulls it taut about the corners 1.14, 115, 116 and 117. These corners are accordingly maintained smoothly rounded around the fold in the interior stiffening tube. The fold of the bag wall proper for closure, which is accomplished by folding the flexible bag material over the edges 102102 is accomplished in the usual way and these serrations 102 accordingly deflect slightly, as previously described, thereby relieving stress concentration at such edges. The same is true along the edges 103, 104, 107, 108 and 110 and 111.

It will be understood that the reinforcing cardboard members may, if desired, be placed between the plies of a multiple ply flexible walled bag. Thus, in a two-ply bag the cardboard may be inserted simply between the inner and outer plies. Where there are more than two plies it is preferable to insert the cardboard stiffener elements between the innermost and the next innermost plies. There is an advantage in this in that a very low grade cardboard, which might possess an odor or dark appearance, may be utilized, the inner ply of the bag being composed of slick paper, moisture impervious paper or the like.

In any of the modifications shown, the stiff reinforcing elements may be held in place on the interior of the bag wall or between the plies by ordinary adhesives. The adhesive is preferably not spread entirely to the edge of the marginally weakened reinforcing elements so as not to stiffen such edges which are intentionally weakened so as to bend. Where the material filled into the bag is rather coarse, one or two lines of adhesive or spots of adhesive are usually sutficient for holding the reinforcing members in place, since when the bag is filled the outward pressure of the bulk solid granular material is sufiicient to stabilize the reinforcing elements in place. In other instances, a line of adhesive is made around the edge of the margin of the reinforcing panel so as to prevent fine granular material, such as flour or sugar, from dusting into the space between the panel and the bag and causing local lens-shaped bulges to occur. In the modifications shown in Figure 18 the vertical edges of those portions of the reinforcing element which overlap the sides, if desired, may be free from marginal weakening since when the bag is filled, the flexible bag wall (being merely a part of the side) is not ordinarily pulled tight around or folded over these edges. As an illustration edges 81A and 81B are shown marginally weakened, whereas edges 96A and 96B are not. Accordingly, there is less tendency for the bag wall to break or tear through at such edges than at the upper and lower edges of the reinforcing elements. The edges 107, 108, 110 and 111 of the modification shown in Figure 19 likewise need not be weakened if not desired.

As many apparently widely different embodiments of the invention may be made without departing from the spirit and scope thereof, it is to be understood that I do not limit myself to the specific embodiments herein.

n ennas 9 What I claim is:

1. A container composed of relatively thin flexible material formedto provide a container space substantially in the form of a rectangular parallelepipedon when said container is filled and closed, said container being foldable to a flat condition when empty, a stiff panel for reinforcing a portion of the area of said thin flexible material which forms one of the sides of said parallelepipedon shaped container when the container is filled and closed, said panel being secured to the thin flexible material in a position such that some of its edges are substantially at the junction ofadjacent faces of said parallelepipedon -when the container is opened, said edges of said panel being progressively weakened towards the terminal edge of -the panel, thus permitting said portions to deflect slightly and with the thin flexible layer of the container form a neat short-radius bend at said junctions when the container is filled and closed, stresses being thereby transferred between the panel and the adjacent overlying flexible material throughout the area of said short radius bends.

2. A container composed of relatively thin flexible "material formed to provide a containerspace substantially "in 'the form of a rectangular parallelepipedon when said containeris filledand closed, said container being toldable to a flat conditionwhen empty, a stiff panel for reinforcing a portion of the area of said thin flexible material ":Which' forms one of the sides of said parallelepipedon shaped container when the container is filled and closed,

said panel being secured to the thin flexible material in a position such that some of its edges are substantially at the jun'ctionof adjacent faces of said parallelepipedon when the container is opened, said edges of said panel being serrated so as to be progressively weakened towards the terminal edged the panel, thus permittingsaid'pontions'to deflect slightly and with the thiti flexible layer of the container form aneat short-radius'bend at said junctions when'the container isfilled and closed,

' stresses beingth'ereby transferred between the panel and the adjacent overlying flexible material throughout'the area of said short radius bends.

3.'A container composed of relatively thin flexible material formed to provide acontainerspace substantially in the form of a rectangularparallelepipedon when said container is filled and closed, said container being fold able to aflat condition when'empty, a stiff panel for reinforcing at least a portion of the area of said thin flexible material which forms one'of the sides of said parallelepipedon shaped container :when the container -is filled and closed, said panel being secured tothe thin flexible material in a position such'th-art at least some of its edges are substantially at the junction of adjacent faces of said parallelepipedon when the container is opened, said edges of said panel being partially cut through on a serrated line so as to be progressively weakened towards the terminal edge of the panel, thus permitting said portions to deflect slightly and with the thin flexible layer of the container form a neat short-radius bend at said junctions when the container is filled and closed, stresses being thereby transferred between the panel and the adjacent overlying flexible material throughout the area of said short radius bends.

4. A container composed of relatively thin flexible material formed to provide a container space substantially in the form of a rectangular parallelepipedon when said container is filled and closed, said container being foldable to a flat condition when empty, a stiff panel for reinforcing at least a portion of the area of said thin flexible material which forms one of the sides of said parallelepipedon shaped container when the container is filled and closed, said panel being secured to the thin flexible material in a position such that at least some of its edges are substantially at the junction of adjacent faces of said parallelepipedon when the container is opened, said edges of said panel being chamfered so as to be progressively I panel and weakened towards the terminal edge of the panel, thus permitting said portions to deflect slightly and with the thin flexible layer of the container form a neat shortradius bend at said junctions when the container is filled and closed, stresses being thereby transferred between the panel and the adjacent overlying flexible material throughout the area of said short radius bends.

5. A container composed of relatively thin flexible material formed to provide a container space substantially in the form of a rectangular parallelepipedon when said container is filled and closed, said container being foldable to a flat conditionwhen empty, a stiff panel for reinforcing at least a portion of the area of said thin flexible material which forms one of the sides of said parallelepipedon shaped container when the container is filled and closed, said panel being secured to the thin flexible material in a position such that at least some of its edges are substantially at the junction of adjacent faces of said parallelepipedon when the container is opened, said edges of said panel being partially cut through on a line parallel to the terminal edge of the panel and the cut material is removed, said edges of said, panel being progressively weakened towards the terminal edge of the panel, thus permitting said portions to deflect slightly and with the thin flexible layer of the container form a neat short-radius bend at said junctions when the container is filled and closed, stresses being thereby transferred between the panel and the adjacent overlying flexible material throughout the area of said short radius bends.

6. A container composed of multiple plies of relatively thin flexible material formed to provide a container space substantially in the form of a rectangular parallelepipedon when said container is filled and closed, said container being foldable to a flat condition when empty, a stiff panel on the inner surface of the innermost of said plies "for reinforcing at least a portion of the area of said thin flexible material which forms one of the sides of said parallelepipedon shaped container when the container is "filled and closed, said panel beingsecured to the thin flexible material in a position such that at least some of its edges are substantially at the junction of adjacent faces of said parallelepipedonwhen the container is opened, said edges of said panel being progressively weakened towards't-he terminal edge of the panel, thus permitting said portions to deflect slightly and with the thin flexible layer of the container form a neat short-radius bend at said junctions when the container is filled and closed, stresses being thereby transferred between the the adjacent overlying flexible material throughout-the'area'of said short radius bends.

7. A container composed of multiple plies of relatively thin tflexible material formed to provide a container space substantially in the form of a rectangular parallelepipedon when said container is filled and closed, said container being foldable to a flat condition when empty, a stiff panel secured between said plies for reinforcing at least a portion of the area of said thin flexible material which forms one of the sides of said parallelepipedon shaped container when the container is filled and closed, said panel being secured to the thin flexible material in a position such that at least some of its edges are substantially at the junction of adjacent faces of said parallelepipedon when the container is opened, said edges of said panel being progressively weakened towards the terminal edge of the panel, thus permitting said portions to deflect slightly and with the thin flexible layer of the container form a neat short-radius bend at said junctions when the container is filled and closed, stresses being thereby transferred between the panel and the adjacent overlying flexible material throughout the area of said short radius bends.

8. A flat foldable bag composed of flexible material, said bag being folded so as to lie flat when empty and capable of being opened to form a substantially rectangular bag having a front, back, sides, top and bottom, a

relatively stiff reinforcing panel adhesively secured to the inner surface of the bag coextensive with the front and the back, the marginal edge of said panel being serrated so as to permit the panel to bend transversely adjacent the junction of the front and back with the sides and ends of the bag, when the bag is opened and filled, and the weakened edges of the panel being thus both neatly bent along a short radius at said edges, said front and back being maintained substantially flat by the rein forcing action of the panel.

9. A flat foldable bag composed of flexible material, said bag being folded so as to lie flat when empty and capable of being opened to form a substantially rectangular bag having a front, back, sides, top and bottom, a relatively stiff reinforcing panel adhesively secured to the inner surface of the bag, coextensive with the front and the back, the marginal edge of said panel being chamfered so as to permit the panel to bend transversely adjacent the junction of the front and back with the sides and ends of the bag, when the bag is opened and filled, a flexible material of which the bag is made, and the weakened edges of the panel being thus both neatly bent along a short radius at said edges, said front and back being maintained substantially flat by the reinforcing action of the panel.

10. A flat foldable bag composed of flexible material, said bag being folded so as to lie flat when empty and capable of being opened to form a substantially rectangular bag having a front, back, sides, top and bottom, a relatively stiff reinforcing panel adhesively secured to the inner surface of the bag, coextensive with the front and the back, the marginal edge of said panel being progressively outwardly weakened so as to permit the panel to bend transversely adjacent the junction of the front and back with the sides and ends of the bag, when the bag is opened and filled, a flexible material of which the bag is made, and the weakened edges of the panel being thus both neatly bent along a short radius at said edges, said front and back being maintained substantially flat by the reinforcing action of the panel.

11. A bag container composed of relatively thin flexible material formed to provide a container space substantially in the form of a rectangular parallelepipedon when said container is filled and closed, said container being foldable to a flat condition when empty, a stiff panel for reinforcing said thin flexible material which forms one of the sides of said parallelepipedon shaped container when the container is filled and closed, said panel extending throughout the area thereof, opposed marginal edges of said panel being progressively weakened towards the terminal edge of the panel, thus permitting said edges to deflect slightly, stresses being thereby transferred between the panel and the adjacent overlying 12 flexible material throughout the area of said progressively weakened edges.

12. A container composed of relatively thin flexible material formed to provide a container space substantially in the form of a rectangular parallelepipedon when said container is filled and closed, said container being foldable to a flat condition when empty, stiff panels for reinforcing portions of the area of said thin flexible material which form opposed sides of said parallelepipedon shaped container when the container is filled and closed, said panels being secured to the thin flexible material in a position such that some of their edges are substantially at the junctures of adjacent faces of said parallelepipedon when the container is open, said edges of said panels being progressively weakened toward the terminal edges of the panels thus permitting said portions to deflect slightly and with the thin flexible layer of the container form a neat short radius bend at said junctures when the container is filled and closed, stresses thereby being transferred between the panels and the adjacent overlying flexible material throughout the area of the short radius bends.

13. The structure of claim 12 further characterized in that said stiff panels are connected to a third panel reinforcing a portion of the area of said thin flexible material which forms an intermediate side of said parallelepipedon shaped container.

14. The structure of claim 12 further characterized in that said panels are connected by opposed intermediate panels.

References Cited in the file of this patent UNITED STATES PATENTS 294,858 Dick Mar. 11, 1884 1,466,962 Reynolds Sept. 4, 1923 1,624,375 Thom Apr. 12, 1927 1,868,069 Munsen July 19, 1932 2,056,092 Claif Sept. 29, 1936 2,087,467 Sterling Apr. 27, 1937 2,115,802 Dann May 3, 1938 2,124,324 Weeks July 19, 1938 2,134,627 Turner Oct. 25, 1938 2,285,399 Ameson June 9, 1942 2,486,743 Hafiner Nov. 1, 1949 2,533,051 Saunders Dec. 5, 1950 2,582,346 Mullinix Jan. 15, 1952 2,586,301 Castle Feb. 19, 1952 FOREIGN PATENTS 804,959 France Aug. 17, 1936 627,711 Great Britain Aug. 15, 1949 

